Ports and Protocols

Question 1

What are Network Ports?

Answer 1

• Ports are essentially endpoints where network connections can start and or end
• Better explained with an apartment building mailbox example!

Question 2

What are Network Protocols?

Answer 2

• Protocol: “A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network.”
• Your OS will choose a different protocol to communicate over the network depending on what you’re doing
• Why? Important for troubleshooting!

Question 3

TCP (Transmission Control Protocolo)
UDP (User Datagram Protocol)

Answer 3

A deep dive into TCP/UDP is a bit beyond scope, but basically, the difference TCP and UDP are methods of sending traffic between hosts. The difference between TCP and UDP is, TCP is considered
“connection oriented” protocol and is used when it’s absolutely imperative that all data is successfully transmitted (for example, when sending files) at the cost of speed.
UDP offers best-effort delivery of data, but is much quicker with less overhead.

Question 4

Well Known Protocols & Their Port Numbers

Answer 4

HTTP (Hypertext Transfer Protocol)
• Port: 80 (TCP)
HTTPS (Hypertext Transfer Protocol Secure)
• Port: 443 (TCP)
DHCP (Dynamic Host Configuration Protocol)
• Port: 67 and 68 (UDP)
DNS (Domain Name System)
• Port: 53 (Both TCP and UDP)
RDP (Remote Desktop Protocol)
• Port: 3389 (TCP)
SSH (Secure Shell)
• Port: 22 (TCP)

Question 5

HTTP (TCP 80) / HTTPS (TCP 443)

Answer 5

These protocols are used by your computer usually when browsing the Internet.
Possible to be used by other programs in the background

Question 6

DHCP (UDP 67 and 68)

Answer 6

This protocol is used to assign an IP address to devices when they are first connected to the network

Question 7

DNS stands for Domain Name System (or Domain
Naming Server)
Primary Goal: Convert human readable domain names (such as www.google.com) to IP addresses, which computers can use and understand.

Answer 7

DNS stands for Domain Name System (or Domain
Naming Server)
Primary Goal: Convert human readable domain names (such as www.google.com) to IP addresses, which computers can use and understand.

Question 8

Remote Desktop Protocol (RDP, TCP 3389)

Answer 8

RDP is used when remotely connecting from one computer to another to gain a remote desktop GUI. The computer being connected to is typically “listening” for a connection on TCP port 3389.

Question 9

Secure Shell (SSH, TCP 22)

Answer 9

SSH is used when remotely connecting from one computer to another and spawning a command line. The computer being connected to is typically “listening” for a connection on TCP port 22.

Question 10

ICMP (No Port!)

Answer 10

• IMP stands for “Internet Control Message Protocol”.
• All you have to know is this is the protocol that “ping” uses. o Ping is a command tool used to check if another computer is reachable on the network.line